Biopsy device having a ratchet drive mechanism for driving a biopsy probe assembly

ABSTRACT

A biopsy device includes a first cannula having a first aperture, a second cannula having a second aperture, and a driver unit. The second cannula is disposed co-axially with the first cannula. At least one of the first aperture and the second aperture has a cutting edge. The driver unit has a ratchet drive mechanism operatively coupled to the first cannula and the second cannula. The ratchet drive mechanism includes a first gear fixedly attached to the first cannula. A second gear is fixedly attached to the second cannula. A torsion spring has a first end portion connected to the first gear and a second end portion connected to the second gear. The torsion spring stores energy which when released drivably rotates one of the first gear and the second gear relative to the other of the first gear and the second gear.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is related to PCT/US2009/037289.

MICROFICHE APPENDIX

None.

GOVERNMENT RIGHTS IN PATENT

None.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to medical devices, and, moreparticularly, to a biopsy device having a ratchet drive mechanism fordriving a biopsy probe assembly.

2. Description of the Related Art

A typical biopsy device includes a biopsy driver to which there ismounted a biopsy probe assembly. The biopsy driver typically isconfigured to be reusable, whereas the biopsy probe assembly isconfigured to be disposable. The biopsy driver provides theelectromechanical power used to drive the biopsy probe assembly.Typically, the biopsy probe assembly has a cannula configured with asample notch and a tissue sample chamber, and has a tissue cuttingmechanism associated with the cannula. During a biopsy procedure, vacuumassistance may be used to help draw tissue through the sample notch andinto the sample chamber and maximize the amount of tissue obtained witheach sample. Some biopsy devices, commonly referred to as singleinsertion, multiple samples, or S1MS devices, utilize sample acquisitionand delivery mechanisms that allow multiple samples to be acquired froma given lesion region without removing and reinserting the needle aftereach sample. One type of cutting mechanism used in a vacuum assistedS1MS biopsy device uses rotational and linear motion of a cutter withrespect to the sample notch to sever the tissue drawn through the samplenotch into the tissue sample chamber. Vacuum is applied to transport thetissue from the tissue sample chamber of the cannula to a samplecollection basket. This process may be repeated until the desired amountof tissue has been obtained.

Also, such a typical biopsy device utilizes a biopsy driver havingelectrical power in the form of a rechargeable battery to facilitatemotor driven linear and rotational movement of the cannula and/or thetissue cutting mechanism of the biopsy probe assembly. Such use of motordriven components to drive the cannula and/or the tissue cuttingmechanism in the biopsy driver adds cost to the overall biopsy device.

It would be desirable to reduce the cost of the biopsy device withoutsacrificing the ability to consistently collect high quality tissuesamples.

SUMMARY OF THE INVENTION

The present invention provides a biopsy device having a ratchet drivemechanism that stores energy for driving a cutting component of a biopsyprobe assembly to harvest a tissue sample during a biopsy procedure.

The invention, in one form thereof, is directed to a biopsy device. Thebiopsy device includes a first cannula, a second cannula and a driverunit. The first cannula has a first side wall defining a first lumen.The first cannula has a first proximal end and a first distal end. Thefirst cannula has a first aperture extending through the first side wallto the first lumen proximal to the first distal end. The first cannulahas a longitudinal axis. A second cannula has a second side walldefining a second lumen. The second cannula has a second proximal endand a second distal end. The second cannula has a second apertureextending through the second side wall to the second lumen proximal tothe second distal end. The second cannula is disposed co-axially withthe first cannula. At least one of the first aperture and the secondaperture has a cutting edge. The driver unit has a ratchet drivemechanism operatively coupled to the first cannula and the secondcannula. The ratchet drive mechanism includes a first gear, a secondgear and a torsion spring. The first gear is fixedly attached to thefirst cannula. The second gear is fixedly attached to the secondcannula. The torsion spring is located between the first gear and thesecond gear. The torsion spring has a first end portion and a second endportion. The first end portion is connected to the first gear and thesecond end portion is connected to the second gear. The ratchet drivemechanism is configured such that the torsion spring stores energy whichwhen released drivably rotates one of the first gear and the second gearrelative to the other of the first gear and the second gear.

The invention, another form thereof, is directed to a biopsy device thatincludes an outer cannula having a first side wall defining a firstlumen. The outer cannula has a first aperture extending through thefirst side wall to the first lumen. The outer cannula has a longitudinalaxis. An inner cannula has a second side wall defining a second lumen.The inner cannula has a second aperture extending through the secondside wall to the second lumen. The inner cannula is disposed co-axiallywith the outer cannula in the first lumen. At least one of the firstaperture and the second aperture has a cutting edge. A ratchet drivemechanism is operatively coupled to the outer cannula and the innercannula. The ratchet drive mechanism includes a first gear fixedlyattached to the outer cannula. A second gear is fixedly attached to theinner cannula. A torsion spring is located between the first gear andthe second gear. The torsion spring has a first end portion and a secondend portion. The first end portion is connected to the first gear andthe second end portion is connected to the second gear. An outer cannulaadvance actuator is configured to rotate the first gear in a clockingmanner in a first rotational direction. An inner cannula advanceactuator is configured to rotate the second gear in a clocking manner ina second rotational direction opposite to the first rotationaldirection. An outer cannula slide actuator has a first cantilever pawl.The outer cannula slide actuator is configured to selective engage thefirst gear, wherein when the first cantilever pawl is engaged with thefirst gear, the first gear and the outer cannula are prevented fromrotation in the second rotational direction. An inner cannula slideactuator has a second cantilever pawl. The inner cannula slide actuatoris configured to selective engage the second gear, wherein when thesecond cantilever pawl is engaged with the second gear, the second gearand the inner cannula are prevented from rotation in the firstrotational direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a perspective view of a biopsy device including a driver unitand a probe assembly, configured in accordance with an embodiment of thepresent invention;

FIG. 2 shows a vacuum source and a tissue sample receptacle, and a gearunit of a ratchet drive mechanism, contained in the driver unit of thebiopsy device of FIG. 1, with the tissue sample receptacle being coupledin fluid communication with the probe assembly and decoupled from thevacuum source;

FIG. 3A is an exploded view of the probe assembly of FIG. 1, andincluding two gears of the gear unit of FIG. 2;

FIG. 3B is a cross-section view of the outer cannula of FIG. 3A takenalong line 3B-3B;

FIG. 3C is a cross-section view of the inner cannula of FIG. 3A takenalong line 3C-3C;

FIG. 4 is an assembled view of the probe assembly of FIG. 3A having therespective apertures of the outer cannula and inner cannula inalignment, and including the gear unit;

FIG. 5 is a cross-section view of the probe assembly of FIG. 4 takenalong line 5-5, showing tissue being drawn through a tissue sampleaperture;

FIG. 6 is a cross-section view of the probe assembly of FIG. 2 takenalong line 6-6;

FIG. 7 is an enlarged perspective view of the gear unit of the ratchetdrive mechanism of FIG. 1;

FIG. 8 is a disassembled view of the gear unit of FIG. 7, with the gearslaid open to expose the respective interior features of the gears and toexpose a torsion spring housed inside the gear unit;

FIG. 9 is a right perspective view of the driver unit and biopsy probeassembly of FIG. 1, with the primary housing removed to expose theinterior of the drive housing that mounts the ratchet drive mechanism;

FIG. 10 is a left perspective view of the driver unit and biopsy probeassembly of FIG. 1, with the primary housing removed to expose theinterior of the drive housing that mounts the ratchet drive mechanism;

FIG. 11 is a proximal end view of the driver unit and biopsy probeassembly of FIG. 1, with the primary housing removed to expose theinterior of the drive housing that mounts the ratchet drive mechanism;

FIG. 12 is a perspective view of the ratchet drive mechanism and biopsyprobe assembly of FIG. 9, with the drive housing removed;

FIG. 13 is an enlarged perspective view of the ratchet drive mechanismof FIG. 12;

FIG. 14 is an enlarged top view of the ratchet drive mechanism of FIG.12; and

FIG. 15 is an enlarged top view of the ratchet drive mechanismcorresponding generally to FIG. 14, but with the outer cannula slideactuator positioned in the firing position.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate an embodiment of the invention, and such exemplifications arenot to be construed as limiting the scope of the invention in anymanner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and particularly to FIG. 1, there is showna biopsy device 10 configured in accordance with an embodiment of thepresent invention. Biopsy device 10 includes a driver unit 12 and abiopsy probe assembly 14.

Driver unit 12 includes a primary housing 16 and a drive housing 18.Primary housing 16 serves as a handle that is grasped by the hand of auser.

In the present embodiment, biopsy probe assembly 14 is permanentlymounted to driver unit 12, in which case biopsy device 10 is made to beentirely disposable. Primary housing 16 is connected to drive housing18, for example, by permanent connection, e.g., adhesive, weld, etc.Alternatively, drive housing 18 and biopsy probe assembly 14 may beremovably mounted to primary housing 16, such that drive housing 18 andbiopsy probe assembly 14 by the formed as a disposable unit separablefrom primary housing 16.

Drive housing 18 contains a ratchet drive mechanism 20 having aplurality of control actuators 22 (e.g., buttons and sliders), and withthe plurality of control actuators 22 being accessible external to drivehousing 18. Ratchet drive mechanism 20 is configured to operate biopsyprobe assembly 14 to sever and receive one or more tissue samples from apatient's body. Ratchet drive mechanism 20 and the plurality of controlactuators 22 are described in greater detail below.

Referring also to FIG. 2, primary housing 16 contains a power unit 24, avacuum source 26, and a tissue sample receptacle 28. Power unit 24includes a rechargeable battery and control circuitry to power andcontrol vacuum source 26. Vacuum source 26 may be, for example, a drivenvacuum pump, such as for example a battery/motor assisted diaphragm pumpor gear driven syringe-type pump. Alternatively, power unit 24 may bereplaced by an on-board gas supply to drive vacuum source 26.

Vacuum source 26 is coupled in fluid communication with tissue samplereceptacle 28 via a fluid coupling 30. Fluid coupling 30 may be, forexample, in the form of a mating seals arrangement or a conduit/sealarrangement. Tissue sample receptacle 28 is coupled in fluidcommunication with biopsy probe assembly 14 by a fluid coupling 32.Fluid coupling 32 may be, for example, in the form of a conduit/sealarrangement or mating seals arrangement.

Accordingly, negative pressure generated by vacuum source 26 iscommunicated to biopsy probe assembly 14 via tissue sample receptacle28. Each tissue sample harvested by biopsy probe assembly 14 istransported by the vacuum generated by vacuum source 26 through biopsyprobe assembly 14 to tissue sample receptacle 28. Tissue samplereceptacle 28 may include, for example, a mesh basket (not shown) tocollect the harvested tissue samples. The mesh basket and/or thecollected tissue samples may be accessed through a door 16-1 of primaryhousing 16.

Referring also to FIGS. 3A-3C, 4, 5, and 6, biopsy probe assembly 14includes an outer cannula 34 and an inner cannula 36.

Outer cannula 34 has a first side wall 34-1 defining a first lumen 34-2.Outer cannula 34 has a first proximal end 34-3, a first distal end 34-4,and a first aperture 38 extending through first side wall 34-1 to thefirst lumen 34-2 at a location proximal to first distal end 34-4. Aneedle tip 40 is located at first distal end 34-4 of outer cannula 34. Alongitudinal axis 42 of biopsy probe assembly 14 passes centrallythrough first lumen 34-2 of outer cannula 34 parallel to a longitudinalextent 34-5 of outer cannula 34.

Inner cannula 36 is disposed co-axially with outer cannula 34 withrespect to longitudinal axis 42. Inner cannula 36 has a second side wall36-1 defining a second lumen 36-2. Inner cannula 36 has a secondproximal end 36-3, a second distal end 36-4, and a second aperture 44extending through second side wall 36-1 to second lumen 36-2 at alocation proximal to second distal end 36-4. Longitudinal axis 42 ofbiopsy probe assembly 14 passes centrally through second lumen 36-2 ofinner cannula 36 parallel to a longitudinal extent 36-5 of inner cannula36.

Vacuum source 26 is in fluid communication with inner cannula 36, andmay establish a continuous or intermittent negative pressure in secondlumen 36-2 of inner cannula 36.

In the present embodiment as shown in FIGS. 2-6, first aperture 38 has alongitudinal edge 38-1 spaced apart from a longitudinal edge 38-2, witha longitudinal extent 38-3 of first aperture 38 being parallel tolongitudinal axis 42. Second aperture 44 has a longitudinal edge 44-1spaced apart from a longitudinal edge 44-2, with a longitudinal extent44-3 of second aperture 44 being parallel to longitudinal axis 42. Atleast one of first aperture 38 of outer cannula 34 and second aperture44 of inner cannula 36 has a cutting edge 46 that is sharpened to razorsharpness. For example, cutting edge 46 may be formed on one or more oflongitudinal edges 38-1, 38-2, 44-1 and 44-2. Also, for example, the oneor more of longitudinal edges 38-1, 38-2, 44-1 and 44-2 having cuttingedge 46 may have an elliptical shape so that cutting edge 46 iscorrespondingly elliptical to aid in severing tissue.

For purposes of the discussion that follow, there is defined a firstrotational direction 52 and a second rotational direction 54. From theperspective of driver unit 12 toward biopsy probe assembly 14, firstrotational direction 52 is in a clockwise direction around longitudinalaxis 42 and second rotational direction 54 is in a counterclockwisedirection around longitudinal axis 42.

Ratchet drive mechanism 20 of driver unit 12 is operatively configuredto rotate inner cannula 36 in the first rotational direction 52, oralternatively in second rotational direction 54, to sequentiallyposition second aperture 44 at one of a plurality of angular radialpositions relative to longitudinal axis 42 during a biopsy procedure topermit the taking of biopsy samples at angular radial positions aroundlongitudinal axis 42 without manually rotating the entirety of driverunit 12. During a cocking operation, first aperture 38 of outer cannula34 and second aperture 44 of inner cannula 36 are rotated into radialalignment by ratchet drive mechanism 20 to form a tissue sample aperture48 to permit the tissue 50 to be biopsied to be drawn by vacuum into thesecond lumen 36-2 of inner cannula 36. During a firing operation,ratchet drive mechanism 20 of driver unit 12 is operatively configuredto rapidly rotate outer cannula 34 relative to inner cannula 36 insecond rotational direction 54 to sever the tissue 50 drawn throughtissue sample aperture 48 and into second lumen 36-2 of inner cannula36.

In the present embodiment, as shown in FIGS. 4 and 5, a maximum openingsize of tissue sample aperture 48 is equal to the smaller of arespective opening size for each of first aperture 38 of outer cannula34 and second aperture 44 of inner cannula 36. In some implementations,it may be desirable for first aperture 38 and second aperture 44 to beof substantially the same size.

Referring to FIGS. 2-8, ratchet drive mechanism 20 of driver unit 12includes a gear unit 56 that includes a outer cannula gear 58, an innercannula gear 60, and a torsion spring 62. Outer cannula gear 58 isfixedly attached to outer cannula 34 for rotation about longitudinalaxis 42. Inner cannula gear 60 is fixedly attached to inner cannula 36for rotation about longitudinal axis 42. As used herein, the term“fixedly attached” means that the respective gear and cannula are notcapable of independent movement relative to each other.

Referring to FIGS. 7 and 8, outer cannula gear 58 is a round gear havinga periphery 64 and having a plurality of ratchet teeth 66 positionedaround periphery 64. Each of the plurality of ratchet teeth 66 relativeto all other of the plurality of ratchet teeth 66 is uniform butasymmetrical in configuration. As best shown in FIG. 8, in the presentembodiment, there are twelve identical asymmetrical ratchet teeth, withratchet tooth 66-1 being representative of a common configuration ofeach of the plurality of ratchet teeth 66. Ratchet tooth 66-1 has aminor slope (bisecting periphery 64 at an acute angle, e.g., in a rangeof 15-45 degrees) on an outer surface 68 and a major slope (bisectingperiphery 64 at an angle equal to or greater than a right angle, e.g.,≥90 degrees) on a drive surface 70. Accordingly, outer cannula gear 58is configured to be externally driven by an external force F1 acting ondrive surface 70 of each of the plurality of ratchet teeth 66. As such,outer cannula gear 58 is oriented on outer cannula 34 so as to rotateouter cannula 34 in first rotational direction 52 when acted on by theexternal force F1.

Inner cannula gear 60 is a round gear having a periphery 74 and having aplurality of ratchet teeth 76 positioned around periphery 74. Each ofthe plurality of ratchet teeth 76 relative to all other of the pluralityof ratchet teeth 76 is uniform but asymmetrical in configuration. Asbest shown in FIG. 8, in the present embodiment, there are twelveidentical asymmetrical ratchet teeth, with ratchet tooth 76-1 beingrepresentative of a common configuration of each of the plurality ofratchet teeth 76. Ratchet tooth 76-1 has a minor slope (bisectingperiphery 74 at an acute angle, e.g., in a range of 15-45 degrees) on anouter surface 78 and a major slope (bisecting periphery 74 at an angleequal to or greater than a right angle, e.g., >90 degrees) on a drivesurface 80. Accordingly, inner cannula gear 60 is configured to beexternally driven by an external force F2 acting on drive surface 80 ofeach of the plurality of ratchet teeth 76. As such, inner cannula gear60 is oriented on inner cannula 36 so as to rotate inner cannula 36 inthe second rotational direction 54 when acted on by the external forceF2. Also, as such, within gear unit 56, the asymmetrical orientation ofthe plurality of ratchet teeth 76 of inner cannula gear 60 is oppositeto the asymmetrical orientation of the plurality of ratchet teeth 66 ofouter cannula gear 58.

FIG. 8 shows gear unit 56 separated into the individual components, towit: outer cannula gear 58, inner cannula gear 60, and a torsion spring62. In FIG. 8, outer cannula gear 58 is being viewed in a direction fromfirst proximal end 34-3 to first distal end 34-4 of outer cannula 34(see FIG. 3A), and inner cannula gear 60 is being viewed in a directionfrom second distal end 36-4 toward second proximal end 36-3 of innercannula 36 (see FIG. 3A), so as to expose the mating gear side surfaces,i.e., surface 82 of outer cannula gear 58 and surface 84 of innercannula gear 60.

Torsion spring 62 is configured in the present embodiment as a coilspring having a plurality of coils 86 having a width W formed from acontinuous length of wire having opposing end portions 88 and 90. Energymay be stored in torsion spring 62 by rotating one of, or both of, endportion 88 and end portion 90 relative to the other around longitudinalaxis 42, to in effect tighten (wind) the plurality of coils 86.

Outer cannula gear 58 includes a spring recess 92 having a depth at arecessed surface 94 sufficient to receive the width W of torsion spring62. In recessed surface 94 there is located a hole 96 for receiving endportion 88 of torsion spring 62. A pin 98, e.g., a cylindrical pin,projects outwardly from surface 82 of outer cannula gear 58 external tospring recess 92.

Inner cannula gear 60 includes a hole 100 located in surface 84 forreceiving end portion 90 of torsion spring 62. Inner cannula gear 60includes an arcuate pin recess 102 having a depth at a recessed surface104 greater than a length of pin 98 of outer cannula gear 58. Arcuatepin recess 102 defines a first stop 106 and a second stop 108, with anangular extent 110 of arcuate pin recess 102 between first stop 106 andsecond stop 108 dictating the maximum relative rotational movement asbetween outer cannula gear 58 and inner cannula gear 60. In the presentembodiment, for example the length of angular extent 110 of arcuate pinrecess 102 is selected to permit a 180 degree maximum relativerotational movement as between outer cannula gear 58 and inner cannulagear 60, and in turn, as between outer cannula 34 and inner cannula 36.

When gear unit 56 is assembled, as shown in FIG. 7, torsion spring 62exerts a slight rotational biasing force to bias pin 98 at first stop106 of arcuate pin recess 102, as illustrated in FIG. 8. As such, outercannula gear 58, and in turn outer cannula 34, is prevented from furtherrotational movement in rotational direction 54 relative to inner cannulagear 60, and in turn outer cannula 36. However, for example, when outercannula gear 58 is acted upon by external force F1, outer cannula gear58, and in turn outer cannula 34, is permitted to rotate in rotationaldirection 52 relative to inner cannula gear 60, and in turn outercannula 36, up to the maximum extend permitted by the angular extent 110of arcuate pin recess 102 in reaching second stop 108, so as to windtorsion spring 62 thereby storing a rotational energy in torsion spring62 which, when released, drives outer cannula 34 rotationally inrotational direction 54 to effect tissue severing.

Referring also to FIGS. 9-15, the plurality of control actuators 22include an outer cannula advance actuator 22-1, an inner cannula slideactuator 22-2, an inner cannula advance actuator 22-3 and an outercannula slide actuator 22-4. As shown in FIGS. 9 and 10, for example,outer cannula advance actuator 22-1, inner cannula slide actuator 22-2,inner cannula advance actuator 22-3 and outer cannula slide actuator22-4 is movably mounted to drive housing 18.

Drive housing 18 includes corresponding actuator slots to respectivelyreceive the plurality control actuators 22, namely actuator slot 18-1,actuator slot 18-2, actuator slot 18-3, and actuator slot 18-4 forrespectively receiving outer cannula advance actuator 22-1, innercannula slide actuator 22-2, inner cannula advance actuator 22-3 andouter cannula slide actuator 22-4. Drive housing 18 includes a side wall18-7 having an inwardly facing guide rail 18-8, and includes a side wall18-9 having an inwardly facing guide rail 18-10. Each of guide rail 18-8and guide rail 18-10 extends substantially parallel to longitudinal axis42.

Outer cannula advance actuator 22-1 is configured as a pushbutton havinga head 112 and a shaft 114. A proximal end 114-1 of shaft is connectedto head 112, and a distal end 114-2 of shaft 114 forms a free end toengage a drive surface 70 of one of the plurality of ratchet teeth 66 ofouter cannula gear 58. A stop 114-3 is connected to shaft 114 at alocation between proximal end 114-1 and distal end 114-2. Extendingdownwardly from head 112 is a spring 116, e.g., a pair of cantileversprings. Shaft 114 extends through actuator slot 18-1 of drive housing18, with head 112 being located external to drive housing 18 and withstop 114-3 and distal end 114-2 being located internal to drive housing18. Spring 116 is interposed between head 112 and an external surface18-5 of drive housing 18 to bias stop 114-3 into engagement with aninternal surface 18-6 of drive housing 18, thus defining a home positionfor outer cannula advance actuator 22-1.

Thus, spring 116 biases head 112 outwardly away from external surface18-5 of drive housing 18. When a user applies a counterforce to head112, spring 116 is compressed as head 112 is depressed toward externalsurface 18-5 and distal end 114-2 of shaft 114 engages a drive surface70 of one of the plurality of ratchet teeth 66 of outer cannula gear 58to incrementally rotate outer cannula gear 58, and in turn rotate outercannula 34, around longitudinal axis 42. When the counterforce appliedto head 112 is released, spring 116 returns outer cannula advanceactuator 22-1 to its home position.

Inner cannula advance actuator 22-3 is configured as a pushbutton havinga head 122 and a shaft 124. A proximal end 124-1 of shaft is connectedto head 122, and a distal end 124-2 of shaft 124 forms a free end toengage a drive surface 80 of one of the plurality of ratchet teeth 76 ofinner cannula gear 60. A stop 124-3 is connected to shaft 124 at alocation between proximal end 124-1 and distal end 124-2. Extendingdownwardly from head 122 is a spring 126, e.g., a pair of cantileversprings. Shaft 124 extends through actuator slot 18-3 of drive housing18, with head 122 being located external to drive housing 18 and withstop 124-3 and distal end 124-2 being located internal to drive housing18. Spring 126 is interposed between head 122 and external surface 18-5of drive housing 18 to bias stop 124-3 into engagement with an internalsurface 18-6 of drive housing 18, thus defining a home position forinner cannula advance actuator 22-3.

Thus, spring 126 biases head 122 outwardly away from external surface18-5 of drive housing 18. When a user applies a counterforce to head122, spring 126 is compressed as head 122 is depressed toward externalsurface 18-5 and distal end 124-2 of shaft 124 engages a drive surface80 of one of the plurality of ratchet teeth 76 of inner cannula gear 60to incrementally rotate inner cannula gear 60, and in turn rotate innercannula 36, around longitudinal axis 42. When the counterforce appliedto head 122 is released, spring 126 returns inner cannula advanceactuator 22-3 to its home position.

Inner cannula slide actuator 22-2 is configured as a slide button havinga head 132, a shaft 134, an elongate guide body 136, and a cantileverpawl 138. Elongate guide body 136 includes a proximal end portion 136-1,a distal end portion 136-2, and a guide channel 136-3. Cantilever pawl138 includes a proximal end 138-1 and a distal end 138-2. Shaft 134extends outwardly from proximal end portion 136-1 of elongate guide body136, and is interposed between head 132 and elongate guide body 136.Cantilever pawl 138 extends inwardly from distal end portion 136-2 in adirection from proximal end 138-1 and distal end 138-2, with distal end138-2 forming a free end to engage a drive surface 80 of one of theplurality of ratchet teeth 76 of inner cannula gear 60.

Inner cannula slide actuator 22-2 is slidably mounted to drive housing18 by guide channel 136-3, which slidably engages guide rail 18-8 ofside wall 18-7 of drive housing 18.

By applying a force to head 132 in direction 160, inner cannula slideactuator 22-2 is slid along actuator slot 18-2 and guide rail 18-8 todisengage distal end 138-2 of cantilever pawl 138 from inner cannulagear 60. As such, inner cannula gear 60, and in turn inner cannula 36are permitted to rotate in either of rotational direction 52 androtational direction 54.

By applying a force to head 132 in direction 162, inner cannula slideactuator 22-2 is slid along actuator slot 18-2 and guide rail 18-8 toengage distal end 138-2 of cantilever pawl 138 with inner cannula gear60. When distal end 138-2 of cantilever pawl 138 is engaged with one ofthe plurality of ratchet teeth 76 of inner cannula gear 60, rotation ofinner cannula gear 60, and in turn inner cannula 36, is prevented inrotational direction 52. However, due to flexure along the length ofcantilever pawl 138 toward distal end 138-2 relative to elongate guidebody 136, rotation of inner cannula gear 60, and in turn inner cannula36, is permitted in rotational direction 54, with a clicking sound beinggenerated each time distal end 138-2 of cantilever pawl 138 drops offone tooth to an adjacent tooth of the plurality of ratchet teeth 76 ofinner cannula gear 60.

Outer cannula slide actuator 22-4 is configured as a slide button havinga head 142, a shaft 144, an elongate guide body 146, and a cantileverpawl 148. Elongate guide body 146 includes a proximal end portion 146-1,a distal end portion 146-2, and a guide channel 146-3. Cantilever pawl148 includes a proximal end 148-1 and a distal end 148-2. Shaft 144extends outwardly from proximal end portion 146-1 of elongate guide body146, and is interposed between head 142 and elongate guide body 146.Cantilever pawl 148 extends inwardly from distal end portion 146-2 in adirection from proximal end 148-1 and distal end 148-2, with distal end148-2 forming a free end to engage a drive surface 80 of one of theplurality of ratchet teeth 76 of outer cannula gear 58.

Outer cannula slide actuator 22-4 is slidably mounted to drive housing18 by guide channel 146-3, which slidably engages guide rail 18-10 ofside wall 18-9 of drive housing 18.

By applying a force to head 142 in direction 162, outer cannula slideactuator 22-4 is slid along actuator slot 18-4 and guide rail 18-10 todisengage distal end 148-2 of cantilever pawl 148 from outer cannulagear 58. As such, outer cannula gear 58, and in turn outer cannula 34,is permitted to rotate in either of rotational direction 52 androtational direction 54.

By applying a force to head 142 in direction 160, outer cannula slideactuator 22-4 is slid along actuator slot 18-4 and guide rail 18-10 toengage distal end 148-2 of cantilever pawl 148 with outer cannula gear58. When distal end 148-2 of cantilever pawl 148 is engaged with one theplurality of ratchet teeth 66 of outer cannula gear 58, rotation ofouter cannula gear 58, and in turn outer cannula 34, is prevented inrotational direction 54. However, due to flexure along the length ofcantilever pawl 148 toward distal end 148-2 relative to elongate guidebody 146, rotation of outer cannula gear 58, and in turn outer cannula34, is permitted in rotational direction 52, with a clicking sound beinggenerated each time distal end 148-2 of cantilever pawl 148 drops offone tooth to an adjacent tooth of the plurality of ratchet teeth 66 ofouter cannula gear 58.

The operation of ratchet drive mechanism 20 in performing a biopsyprocedure will now be described with specific reference to FIGS. 2, 5,and 12-15.

FIGS. 12, 13 and 14 illustrate a start position of inner cannula slideactuator 22-2 and outer cannula slide actuator 22-4, with inner cannulaslide actuator 22-2 being disengaged from inner cannula gear 60 andouter cannula slide actuator 22-4 being engaged with outer cannula slideactuator 22-4. More specifically, in the start position, both of innercannula slide actuator 22-2 and outer cannula slide actuator 22-4 havebeen slid in direction 160 to disengage distal end 138-2 of cantileverpawl 138 of inner cannula slide actuator 22-2 from inner cannula gear 60and to engage distal end 148-2 of cantilever pawl 148 of outer cannulaslide actuator 22-4 with outer cannula gear 58.

Outer cannula advance actuator 22-1 is then depressed to rotate outercannula 34, and in turn rotate inner cannula 36 due to the couplingbetween outer cannula gear 58 and inner cannula gear 60 via torsionspring 62. Thus, with each depression of outer cannula slide actuator22-4, both of outer cannula gear 58 and inner cannula gear 60 will berotated by 30 degrees in rotational direction 52 in a clocking manner toposition first aperture 38 of outer cannula 34 at the desired angularposition for taking a tissue sample.

Once first aperture 38 of outer cannula 34 is at the desired angularposition (e.g., the 3:00 o'clock position as illustrated in FIG. 12,also represented as the 0 degree position illustrated in FIG. 5), innercannula slide actuator 22-2 is slid in direction 162 so that distal end138-2 of cantilever pawl 138 is engaged with inner cannula gear 60 topreventing rotation of inner cannula gear 60 in rotational direction 52.Then inner cannula advance actuator 22-3 is pushed (depressed) a numberof times (maximum of six in the present embodiment) to preload (e.g.,wind) torsion spring 62, thus performing the cocking operation. Witheach depression of inner cannula advance actuator 22-3, inner cannulagear 60 will be rotated by 30 degrees in rotational direction 54 (up to180 degrees) in a clocking manner, while outer cannula slide actuator22-4 prevents rotation of outer cannula gear 58, and in turn outercannula 34, in rotational direction 54. At the conclusion of the cockingoperation, pin 98 of outer cannula gear 58 will be engaged with secondstop 108 of arcuate pin recess 102 of inner cannula gear 60 to preventfurther relative rotation, with second aperture 44 of inner cannula 36having been brought into alignment with first aperture 38 of outercannula 34 to form tissue sample aperture 48. At this time, the cockingoperation is complete.

The vacuum source 26 may be actuated (before, during, or after thecocking operation) to establish a negative pressure in the second lumen36-2 (see FIG. 5) of inner cannula 36 to thereby pull tissue 50 throughthe formed tissue sample aperture 48 and into the second lumen 36-2 ofinner cannula 36. The negative pressure in second lumen 36-2 of innercannula 36 is maintained during the firing (cutting) operation.

To perform the firing (cutting) operation, as illustrated in FIG. 15,outer cannula slide actuator 22-4 is slid in direction 162 to disengagedistal end 148-2 of cantilever pawl 148 from outer cannula gear 58 torelease the preload of torsion spring 62, which results in a rapidrotation of outer cannula 34 in rotational direction 54 relative to thestationary inner cannula 36, so as to sever the tissue 50 in secondlumen 36-2 of inner cannula 36. In the present embodiment, the maximumrelative rotation of outer cannula 34 with respect to inner cannula 36is 180 degrees due to the angular extent 110 of arcuate pin recess 102of inner cannula gear 60. Inner cannula 36 is held stationary by thecontinued engagement of distal end 138-2 of cantilever pawl 138 of innercannula slide actuator 22-2 with inner cannula gear 60. The rotationalvelocity of outer cannula 34 relative to inner cannula 36 is defined,for example, at least in part by the spring stiffness of torsion spring62 and the maximum relative rotation of outer cannula 34 with respect toinner cannula 36 as defined by angular extent 110 of arcuate pin recess102.

Once tissue 50 is severed, the severed tissue sample is transported bythe negative pressure in second lumen 36-2 through inner cannula 36 totissue sample receptacle 28 (see FIG. 2).

If additional tissue samples are desired, both of inner cannula slideactuator 22-2 and outer cannula slide actuator 22-4 are slid indirection 160 to disengage distal end 138-2 of cantilever pawl 138 frominner cannula gear 60 and to reengage distal end 148-2 of cantileverpawl 148 with outer cannula gear 58, so as to return the components ofratchet drive mechanism 20 to the start position illustrated in FIG. 12,and the process described above is repeated.

Due to the configuration of ratchet drive mechanism 20, it is possibleto perform the cocking operation using an alternative process. Forexample, in this implementation initially inner cannula slide actuator22-2 is engaged with inner cannula gear 60 and outer cannula slideactuator 22-4 is disengaged from outer cannula gear 58. Then, innercannula advance actuator 22-3 is pushed (depressed) a number of times toposition second aperture 44 of inner cannula 36 at the desired thedesired angular position (e.g., the 3:00 o'clock position as illustratedin FIG. 12, also represented as the 0 degree position illustrated inFIG. 5). Once the desired angular position is achieved, outer cannula 34is locked from further rotation in rotational direction 54 by slidingouter cannula slide actuator 22-4 into engagement with outer cannulagear 58.

Outer cannula advance actuator 22-1 is then pushed (depressed) a numberof times (maximum of six in the present embodiment) to preload (e.g.,wind) torsion spring 62, thus performing the cocking operation. Witheach depression of outer cannula advance actuator 22-1, outer cannula 34will be rotated by 30 degrees in rotational direction 52 (up to 180degrees), while inner cannula slide actuator 22-2 prevents rotation ofinner cannula gear 60, and in turn inner cannula 36, in rotationaldirection 52. At the conclusion of the cocking operation, pin 98 ofouter cannula gear 58 will be engaged with second stop 108 of arcuatepin recess 102 of inner cannula gear 60 to prevent further relativerotation, with first aperture 38 of outer cannula 34 having been broughtinto alignment with second aperture 44 of inner cannula 36 to formtissue sample aperture 48. At this time, the cocking operation iscomplete.

The establishing of vacuum and the firing operation may then beperformed as previously described.

While this invention has been described with respect to embodiments ofthe invention, the present invention may be further modified within thespirit and scope of this disclosure. This application is thereforeintended to cover any variations, uses, or adaptations of the inventionusing its general principles. Further, this application is intended tocover such departures from the present disclosure as come within knownor customary practice in the art to which this invention pertains andwhich fall within the limits of the appended claims.

1-19. (canceled)
 20. A biopsy device, comprising: a first cannula havinga longitudinal axis; a second cannula disposed co-axially with the firstcannula; a first gear fixedly attached to the first cannula; a secondgear fixedly attached to the second cannula; a torsion spring interposedbetween the first gear and the second gear, the torsion spring beingconnected to each of the first gear and the second gear; a ratchet drivemechanism configured to wind the torsion spring to store energy during acocking operation, and configured to release the energy stored by thetorsion spring during a firing operation to drivably rotate the firstgear to rotate the first cannula relative to the second cannula.
 21. Thebiopsy device of claim 20, comprising: a first cannula advance actuatorconfigured to rotate the first gear in discrete rotational increments ina first rotational direction; and a second cannula advance actuatorconfigured to rotate the second gear in discrete rotational incrementsin a second rotational direction opposite to the first rotationaldirection.
 22. The biopsy device of claim 21, comprising: a first slideactuator having a first cantilever pawl, the first slide actuator beingconfigured to selectively engage the first gear, wherein when the firstcantilever pawl is engaged with the first gear, the first gear and thefirst cannula are prevented from rotation in the second rotationaldirection; and a second cannula slide actuator having a secondcantilever pawl, the second slide actuator being configured toselectively engage the second gear, wherein when the second cantileverpawl is engaged with the second gear, the second gear and the secondcannula are prevented from rotation in the first rotational direction.23. The biopsy device of claim 22, wherein in order to store the energyin the torsion spring, the first slide actuator is positioned to preventrotation of the first gear in the second rotational direction, thesecond slide actuator is positioned to prevent the second gear fromrotation in the first rotational direction, and the second cannulaadvance actuator is depressed at least one time to rotate the secondgear in the second rotational direction to wind the torsion spring. 24.The biopsy device of claim 22, wherein in order to store the energy inthe torsion spring, the first slide actuator is positioned to preventrotation of the first gear in the second rotational direction, thesecond slide actuator is positioned to prevent the second gear fromrotation in the first rotational direction, and the first cannulaadvance actuator is depressed at least one time to rotate the first gearin the first rotational direction to wind the torsion spring.
 25. Thebiopsy device of claim 20, wherein the first cannula is an outer cannulahaving a needle tip and the second cannula is an inner cannulapositioned in the first lumen of the outer cannula.
 26. The biopsydevice of claim 20, wherein the first gear has a first feature and thesecond gear has a second feature, the first feature being engaged withthe second feature to limit an extent of relative rotation between thefirst cannula and the second cannula.
 27. The biopsy device of claim 26,wherein one of the first feature and the second feature is an arcuaterecess having an angular extent that defines the maximum relativerotational movement between the first gear and the second gear.
 28. Thebiopsy device of claim 20, wherein the first gear has a first sidesurface and a pin extending outwardly from the first side surface, andthe second gear has a second side surface and an arcuate pin recesslocated in the second side surface, the pin of the first gear beingpositioned in the arcuate pin recess of the second gear, and wherein amaximum relative rotation of the first cannula with respect to thesecond cannula is defined by an angular extent of the arcuate pinrecess.
 29. The biopsy device of claim 20, wherein the torsion spring isconfigured to generate a rotational velocity of the first cannularelative to the second cannula, and wherein the rotational velocity isdefined, at least in part, by a spring stiffness of the torsion springand a maximum relative rotation of the first cannula with respect to thesecond cannula.
 30. The biopsy device of claim 20, wherein the torsionspring has a width and the first gear has a spring recess locatedbetween the first gear and the second gear, the spring recess beingconfigured to receive the width of the torsion spring.
 31. The biopsydevice of claim 20, wherein the first gear has a first side surface andthe second gear has a second side surface that mates with the first sidesurface of the first gear, the first gear having a spring recess havingan opening adjacent the second side surface of the second gear, and thetorsion spring being positioned in the spring recess between the firstgear and the second gear.